Microfabricated linear accelerometer

A linear accelerometer comprising:

• a substrate;
• a first bank of variable capacitors formed on a first plurality of fixed capacitive plates and a first plurality of movable capacitive plates;
• a second bank of variable capacitors formed on a second plurality of fixed capacitive plates and a second plurality of movable capacitive plates;
• an inertial mass that is linearly movable in response to linear acceleration along a sensing axis, wherein the inertial mass is electrically coupled to said first and second plurality of movable capacitive plates and is arranged so that said first and second movable capacitive plates form capacitive couplings with said first and second plurality of fixed capacitive plates;
• a central member fixed to said substrate and centrally located within said inertial mass and separated therefrom;
• a plurality of support arms extending between the central mass and the inertial mass for supporting the inertial mass and movable capacitive plates relative to the first and second capacitive plates and allowing linear movement of the inertial mass upon experiencing a linear acceleration along the sensing axis and for preventing linear movement along a nonsensing axis;
• a first input electrically coupled to the first plurality of fixed capacitive plates;
• a second input electrically coupled to the second plurality of fixed capacitive plates;
• and
• an output electrically coupled to the plurality of movable capacitive plates for sensing an output signal indicative of linear acceleration sensed along the sensing axis in response to linear movement of the inertial mass.

A micromachined linear accelerometer comprising:

• a substrate;
• a fixed electrode supported on the substrate and including a first plurality of fixed capacitive plates;
• a ring having a central opening and including a plurality of movable capacitive plates at the outer perimeter arranged to provide a capacitive coupling with the first plurality of fixed capacitive plates, said ring being suspended over a cavity and linearly movable relative to the fixed electrode;
• a central member fixed to the substrate and located within the central opening of the ring;
• a plurality of support arms extending between the central member and the ring for supporting said ring relative to said fixed electrode and allowing linear movement of the ring along a sensing axis upon experiencing a linear acceleration along the sensing axis;
• an input electrically coupled to one of either the fixed electrodes and the ring for receiving an input signal;
• and
• an output electrically coupled to the other of the fixed electrode and the ring for providing an output signal which varies as a function of the capacitive coupling and is indicative of linear acceleration along the sensing axis.